A fascinating read. Not having a vacation policy strikes me as an incredibly radical idea.
It sounds so civilized, yet my worry would be that people end up not taking enough time off due to a combination of peer pressure and indifference. In my experience I've found there are a set of people who always struggle to use up a given vacation allowance, and in a situation where there is no allowance I could see the natural behaviour of these people creating pressure on those who enjoy taking time off to take a lot less.